SPOKANE, Wash. (AP) -- The Air Force says a KC-135 air tanker that crashed in Kyrgyzstan last year was yawing to the left and the right so violently that the tail section broke off, causing the aircraft to plunge toward the ground and explode in mid-air.

The accident last May killed a three-member crew from Fairchild Air Force Base in Spokane.

The Air Force released its report on the crash Thursday. The report says a series of factors combined to doom the 50-year-old aircraft.

The most serious was a so-called "Dutch roll," in which the plane started yawing to the left and right and pitching up and down early in the flight. The stresses on the plane became so great that the tail section broke off.